This invention relates to an intravenous catheter and trocar system, and more particularly to a system providing automatic retraction of the trocar after insertion of the catheter into a blood vessel.
Numerous patents disclose syringes which include a system for either automatically or semi-automatically retracting the syringe needle after use, to prevent accidental contact with the needle. One such syringe is shown in Lindemann, et al. U.S. Pat. No. 4,874,382, issued Oct.17, 1989. In addition Kuuli U.S. Pat. No. 4,747,831 shows a structure for manually retracting a catheter trocar after the trocar has been used to insert the catheter into a blood vessel of a patient.
It is an object of the present invention to provide an automatic arrangement for retracting a trocar after use of the trocar to insert a catheter into a blood vessel. It is a further object of the invention to incorporate an automatic trocar retraction system into various types of catheters. Yet another object of the invention is to provide a trocar retraction system which is relatively simple in concept and inexpensive to manufacture.
In accordance with the invention, an intravenous catheter system includes a catheter defining an internal passage and a trocar having an exposed sharpened end extending from the catheter passage when in an extended position, for use in placing the catheter into a patient's blood vessel. The system further includes an insertion device for manual engagement by a user for use in inserting the sharpened end of the trocar, and thereby the catheter, into the blood vessel. The insertion device includes structure defining an internal passage, and the trocar is releasably engaged with the insertion device when the trocar is in its extended position, to extend outwardly from the internal passage and through the catheter passage. Bias means is interconnected between the insertion device and the trocar, for urging retraction of the trocar from its extended position into the catheter passage. A releasable retainer mechanism functions to retain the trocar in its extended position prior to and during insertion of the catheter and the sharpened end of the trocar into the blood vessel, and for releasing engagement between the trocar and the insertion device in response to manual manipulation of the insertion device by the user after placement of the catheter into the blood vessel. Such manual manipulation of the insertion device functions to actuate the releasable retainer mechanism, to provide retraction of the trocar from its extended position into the catheter passage under the influence of the bias means.
In one form of the invention, the insertion device comprises a handle having one or more side walls defining the internal passage, with the handle being removably engaged with the catheter to provide disengagement of the handle from the catheter in response to manual manipulation of the handle after placement of the catheter into the blood vessel. Disengagement of the handle from the insertion device actuates the releasable retainer mechanism, to release engagement between the trocar and the handle and to provide retraction of the trocar from its extended position. The bias means comprises a spring or other biasing means interconnected between the trocar and the handle, to urge withdrawal of the trocar into and through the catheter passage and into the handle passage upon disengagement of the handle from the catheter. The handle passage opens onto an end of the handle, and a plug member is mounted within the handle passage toward the open end of the handle. The plug member defines a passage through which the trocar extends when in its extended position, and the spring is interposed between the trocar and the plug member to draw the trocar through the plug member passage upon disengagement of the handle from the catheter. A retraction head is mounted to the inner end of the trocar, and the spring is located between the plug member and the retraction head. The catheter includes an enlarged outer end portion defining an open outer end leading to an internal cavity, and an inner tubular end portion defining an open inner end and an internal passage extending between the internal cavity and the open inner end. The handle is removably engaged within the internal cavity defined by the enlarged outer end portion of the catheter. The handle plug member is removably engageable within the internal cavity defined by the enlarged outer end portion of the catheter, and the releasable retainer mechanism is mounted to the plug member and interposed between the trocar and the enlarged outer end portion of the catheter. The releasable retainer mechanism functions to release engagement between the handle and the trocar upon removal of the plug member from the internal cavity defined by the enlarged outer end portion of the catheter. The trocar retraction head includes a detent disposed within the plug member passage. The releasable retainer mechanism is engaged with the trocar detent to retain the trocar in its extended position, and is disengaged from the trocar detent upon removal of the plug member from the internal cavity to provide retraction of the trocar under the influence of the spring. In one form, the releasable retainer mechanism includes a pair of retainer wings mounted within a slot formed in the plug member, and engageable between the catheter and the trocar detent when the plug member is engaged within the internal cavity defined by the enlarged outer end portion of the catheter. Removal of the plug member from the catheter internal cavity releases engagement of the retainer wings between the catheter and the trocar detent.
In another form of the invention, the insertion device includes a pair of wings pivotably mounted for movement between a first position in which the wings are positioned substantially together and a second position in which the wings are moved apart. Manual movement of the wings between their first and second positions functions to actuate the releasable retainer mechanism, to release engagement between the trocar and the insertion device and to provide retraction of the trocar from its extended position. The insertion device includes a tubular body defining the internal passage within which the trocar is mounted, and the wings are pivotably mounted to the tubular body. The catheter is mounted to and extends outwardly from the tubular body, and defines an internal passage in communication with the internal passage defined by the body. The bias means, such as a spring, functions to withdraw the sharpened end of the trocar rearwardly into the catheter passage upon release of engagement between the trocar and the insertion device in response to movement of the wings away from their first position. The internal passage defined by the tubular body opens onto the rearward end of the body, and a rearward portion of the trocar extends outwardly from the rearward end of the body. The releasable retainer mechanism includes a hub member mounted to the rearward portion of the trocar, and a detent arrangement interposed between the hub member and the wings for retaining the trocar in its extended position when the wings are in their first position, and for releasing engagement between the wings and the hub member when the wings are moved away from their first position toward their second position. The detent arrangement includes a stud mounted to the hub member, and a recess formed in each wing for receiving a portion of the stud when the wings are in their first position, and for releasing engagement between the stud and the wings when the wings are moved toward their second position. The tubular body defines an external shoulder, and the spring is interposed between the external shoulder and the hub member for urging retraction of the trocar into the catheter passage. The trocar includes a wedge-shaped stop portion disposed within the body passage, for cooperating with wedge structure disposed within the body passage for stopping rearward movement of the trocar under the influence of the bias means when engagement between the trocar and the insertion device is released. A tube may be connected to the rearward portion of the trocar, for communicating blood withdrawn from a patient to a blood collection receptacle.
The invention further contemplates a method of retracting the sharpened end of the trocar after placement of the catheter into the patient's blood vessel, substantially in accordance with the foregoing summary.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.